1273579 (1) 玖、發明說明 【發明所屬之技術領域】 本發明是關於由光記錄媒體進行資訊再生之方法，尤 其是關於由具有複數個資訊記錄層之可覆寫式光記錄媒體 進行資訊再生之方法。並且，本發明是關於用以再生記錄 於光記錄媒體之資訊的資訊再生裝置，尤其是關於用以再 生記錄於具有複數個資訊記錄層之可覆寫式光記錄媒體之 資訊的資訊再生裝置。再者，本發明是關於光記錄媒體， 尤其是關於具有複數個資訊記錄層之可覆寫式光記錄媒體 【先前技術】 就用以記錄數位資料之記錄媒體而言，以往CD或 DVD等代表性的光記錄媒體廣爲消費者使用。近年，對 此種光記錄媒體之記錄容量擴增的需求性逐漸升高，爲達 成此目的而具有各種提案。就該提案之一個例子來說，具 有令光記錄媒體所含的資訊記錄層形成2層構造的提案， 且目前正應用於再生專用光記錄媒體之DVD - Video或 DVD — ROM。在此種再生專用光記錄媒體中，形成於基板 表面的訊洞是資訊記錄層，且此種基板具有介著中間層而 積層的構造。 又，近年，關於使用者可進行資料覆寫的光記錄媒體 (可覆寫式光記錄媒體），已提案有資訊記錄層爲2層構 造式的光記錄媒體（參考日本特開200 1 -2 73 63 8號公報） -6- 1273579 (2) 在資訊記錄層爲2層構造之可覆寫式光記錄媒體中，記錄 膜和夾著記錄膜而形成之介電體膜（保護膜）即爲資訊記 錄層’且該資訊記錄層具有介著中間層而積層之構造。 就可覆寫式光記錄媒體的記錄膜而言，一般可使用相 變化材料，利用結晶狀態時和非結晶狀態時之反射率差來 進行資料的記錄。亦即，在未記錄狀態下記錄膜實質上會 整面形成結晶狀態，而在記錄資料的狀態下記錄膜的預定 部分會形成非結晶狀態，且會形成記錄標記（mark )。爲 使結晶狀態的相變化材料變成非結晶狀態，則可在加熱至 熔點以上的溫度後，加以快速冷卻。反之，爲使非結晶狀 態的相變化材料變成結晶狀態，則可在加熱至熔點以上的 溫度後，加以緩緩冷卻。 此種加熱及冷卻，可藉由調整雷射光束的功率（輸出 )來進行。也就是說，藉由調變雷射光束的強度。不僅得 以將資料記錄於未記錄狀態下的記錄膜，亦可將不同的資 料直接覆寫（direct overwrite)在已記錄有資料的部分。 一般而言，爲將記錄膜加熱至熔點以上的溫度，雷射光束 的功率即爲以具有由記錄功率（Pw )至基底功率（Pb ) 的振幅之脈衝波形來設定的功率，爲了急速冷卻記錄膜， 雷射光束的功率設定爲基底功率（Pb )。此外，爲將記錄 膜加熱至大於結晶化溫度的溫度後，使其緩緩冷卻，雷射 光束的功率設定爲刪除功率（Pe )。此時，刪除功率（pe )是設定爲記錄膜之溫度大於結晶化之溫度但未達熔點的 溫度之位階（level )，藉以進行所謂的固相刪除。 1273579 (3) 於此，在資訊記錄層爲2層構造之可覆寫式光記錄媒 體中’是藉由將雷射光束聚焦於任一資訊記錄層來進行資 料的記錄/再生，所以對從光入射面對較遠側的資訊記錄 層（以下’稱爲「L1層」）進行資料的記錄/再生時， 會經由離光入射面較近側的資訊記錄層（以下，稱爲「L 〇 層」）來照射雷射光束。故L 0層必須具有充足的光透過 率’所以無論L 0層上是否設有反射膜，一般該膜厚須設 得很薄。 然而，根據本案發明者的硏究可知，在資訊記錄層爲 2層構造之可覆寫式光記錄媒體中，在L0層很容易發生 ή己錄fe的記錄狀態隨著資料的再生而劣化之所謂「再生劣 化現象」。可認爲是無論L Q層是否設有反射膜，皆應將 該L0層之膜厚設得很薄，故與具有充分膜厚之反射膜L1 層相比較，散熱性較低之故。也就是說，一般使用金屬來 作爲反射膜的材料，所以L1層中雷射光束的照射所生的 熱會透過熱傳導性高的反射膜快速地散熱，而另一方面可 認爲是，由於L 0層不具有此種熱傳導性高的層，所以雷 射光束的照射所生的熱無法快速地散熱，而會引起再生劣 化現象。 另一方面，近年，將使用於記錄/再生之雷射光束的 波長（λ )和用以聚集雷射光束之接物鏡開口數（n A ) 的比値（λ / N A )設爲7 0 0 n m以下，例如藉由令N A增 至0.7以上，尤其增至〇·85左右，同時，將此雷射光束 的波長λ縮短至200至450nm左右以縮小雷射光束的聚 -8 - 1273579 (4) 焦光點直徑，藉以嘗試記錄大容量的數位資料。如此藉由 利用高NA的接物鏡聚集短波長的雷射光束，以進行資料 的記錄/再生之系統中，由於所聚集之單位面積雷射光束 的能源非常高，故上述L0層的再生劣化現象非常顯著。 【發明內容】 本發明之目的在於提供一種對於具有複數個資訊記錄 層之可覆寫式光記錄媒體之資訊再生方法，且得以抑制再 生劣化現象之資訊再生方法。 並且，本發明之其他目的在於提供一種用以於具有複 數個資訊記錄層之可覆寫式光記錄媒體上記錄資訊的資訊 再生裝置，且得以抑制再生劣化現象之資訊再生裝置。 並且，本發明之另一目的在於提供一種具有複數個資 訊記錄層之可覆寫式光記錄媒體，且得以抑制再生劣化現 象之光記錄媒體。 本發明之目的是藉由對於具至少積層第1及第2資訊 記錄層的光記錄媒體，藉由從光入射面照射雷射光束而再 生資訊之資訊再生方法而達成者，其特徵爲：將上述雷射 光束的波長設爲λ，且將用以聚集上述雷射光束之接物鏡 的開口數設爲ΝΑ時，設定爲；l/NA‘700nm，並且對記 錄於上述第1資訊記錄層的資訊進行再生時，將上述雷射 光束設定爲第1功率；且對記錄於上述第2資訊記錄層的 資訊進行再生時，將上述雷射光束設定爲與上述第1功率 不同的第2功率。 -9- 1273579 (5) 本發明之較佳實施方式中，上述第1資訊記錄層較上 述第2資訊記錄層，位於偏靠上述光入射面側處，且上述 第1功率小於上述第2功率。 本發明之更理想的實施方式中，將上述第1功率設爲 Pr〇’上述第2功率設爲Prl時，設定爲Pr0/Prl<0.9, 以進行資訊再生。 本發明之更理想的實施方式中，上述雷射光束的波長 λ 爲 200 至 45 0nm。 本發明之上述目的是藉由對於具有至少積層第1及第 2資訊記錄層的光記錄媒體，藉由從光入射面照射雷射光 束而再生資訊之資訊再生裝置而達成者，其特徵爲：將上 述雷射光束的波長設爲λ，且將用以聚集上述雷射光束之 接物鏡的開口數設爲ΝΑ時，設定爲又/ NAS 700nm，並 且對記錄於上述第1資訊記錄層的資訊進行再生時，將上 述雷射光束設定爲第1功率；且對記錄於上述第2資訊記 錄層的資訊進行再生時，將上述雷射光束設定爲與上述第 1功率不同的第2功率。 本發明之上述目的是藉由具有至少積層第1及第2資 訊記錄層，且可藉由從光入射面照射雷射光束而再生資訊 之光記錄媒體而達成者，其特徵爲：將上述雷射光束的波 長設爲λ，且將用以聚集雷射光束之接物鏡的開口數設爲 ΝΑ時，設定爲；I / NAS 700nm，並且具有所須的設定資 訊，俾對記錄於上述第1資訊記錄層的資訊進行再生時， 將上述雷射光束設定爲第1功率；且對記錄於上述第2資 -10- 1273579 (6) 訊記錄層的資訊進行再生時，將上述雷射光束設定爲與上 述第1功率不同的第2功率。 本發明之較佳實施方式中，具備作爲上述雷射光束之 光路的光透過層，且上述光透過層的厚度爲30至200//m 〇 根據本發明，對於具有複數個資訊記錄層的光記錄媒 體進行資訊再生時，可抑制再生劣化現象。 【實施方式】 以下，茲參佐附加圖面詳細說明本發明之較佳實施方 式。 第1圖是槪略地顯示本發明之較佳實施方式的光記錄 媒體1 〇之構造剖視圖。 如第1圖所示，本發明實施方式之光記錄媒體1 0具 有基體11、中間層12、光透過層13、設於中間層12和 光透過層13之間的L0層20、設於基體1 1和中間層12 之間的L1層30。L0層20構成位於光入射面13a較近側 的資訊記錄層，其由第1介電體膜2 1、L0記錄膜22和第 2介電體膜2 3所構成。此外，L 1層3 0構成位於光入射面 1 3 a較遠側的資訊記錄層，其由第3介電體膜3 1、L 1記 錄膜3 2、第4介電體膜3 3和反射膜3 4所構成。因此， 本實施方式之光記錄媒體1〇具有2層資訊記錄層（L0層 2 0 和 L 1 層 3 0 )。 基體1 1爲厚度約1 · 1 mm的圓盤狀基板，具有確保光 -11 - 1273579 (7) 記錄媒體1 0的機械強度之功用，且於其表面設有訊號紋 道（groove ) 1 la及紋間面（land ) 1 lb。對L1層30進行 資料的記錄/再生時，這些訊號紋道1 1 a和/或紋間面 11b具有作爲雷射光束的導軌（guide track)之功用。訊 號紋道1 la的深度雖無特別限制，然而宜設爲10至40nm ，訊號紋道1 la的間距宜設爲0.2至0.4 // m。基體1 1的 材料可使用各種材料，例如玻璃、陶瓷或樹脂。而這些當 中，就成形容易度的觀點視之，以樹脂爲宜。此種樹脂具 有例如聚碳酸酯樹脂、烯烴（olefin )樹脂、丙烯基樹脂 、環氧樹脂、聚苯乙烯（polystyrene )樹脂、聚乙烯（ Polyethylene)樹脂、聚丙烯樹脂、矽樹脂、氟系樹脂、 ABS樹脂、和胺基甲酸酯（urethane )樹脂等。其中，就 加工性來說，聚碳酸酯樹脂或烯烴樹脂最爲合適。然而， 因爲基體11並非雷射光束的光路，故不須具有高的光透 過性。 中間層12具有令L0層20與L1層30保持充分距離 的功用，且於其表面設有訊號紋道（groove) 12a及紋間 面（land) 12b。對L0層20進行資料的記錄/再生時， 這些訊號紋道12a和/或紋間面12b具有作爲雷射光束的 導軌（guide track)之功用。訊號紋道12a的深度、間距 宜設定爲相同於設於基體1 1之訊號紋道1 1 a的深度、間 距。再者，中間層12的材料並無特別限制，但以使用紫 外線硬化性丙烯基樹脂爲宜。對L 1層3 0進行資料的記錄 /再生時，中間層1 2會爲雷射光束的光路，故必須具有 -12- 1273579 (8) 充分高的光透過性。 光透過層13是雷射光束的光路，同時，亦構成光入 射面13a，其厚度宜設定爲約3〇至2〇〇//ιη。光透過層13 的材料並無特別限制，然而與中間層1 2 —樣，以使用紫 外線硬化性丙烯基樹脂爲宜。如上所述，由於光透過層 1 3爲雷射光束的光路，故必須具有充分高的光透過性。 L 0 錄膜2 2和L 1 g己錄|吴3 2是由相變化材料所構成 者’利用其在結晶狀態時之反射率與非結晶狀態時之反射 率不同的特性’來進行資料的記錄。就L 0記錄膜2 2及 L1記錄膜3 2的具體材料而言，並無特別限定，然而以使 用SbTe系材料爲宜。SbTe系材料亦可僅爲SbTe，就添 加物來說，可使用加入In、Te、Ge、Ag等的InSbTeGe、 AglnSbTe 、 AgSbTeGe 、 AglnSbTeGe 等。 於此，對L 1層3 0進行資料的記錄/再生時，L0記 錄膜2 2乃爲雷射光束的光路，故必須具有充分的光透過 性，故L 0記錄膜2 2的膜厚係以充分薄於l 1記錄膜3 2 的膜厚之方式設計。具體而言，L1記錄膜32之膜厚宜設 定爲約3至2 0 n m，L 0記錄膜2 2的膜厚宜設定爲L 1記錄 膜32之膜厚的0.3至0.8倍。 以夾住L0記錄膜22而設置的第1介電體膜21及第 2介電體膜23，對於L0記錄膜22乃具有保護膜的功能； 且以夾住L1記錄膜3 2而設置的第3介電體膜3 1及第4 介電體膜3 3，對於L 1記錄膜3 2乃具有保護膜的功能。 第1介電體膜21的厚度宜設定2至200nm，第2介電體 1273579 (9) 膜23的厚度宜設定爲2至200 nm爲宜，第3介電體膜31 的厚度宜設爲2至200nm ’和第4介電體膜33的厚度宜 設定爲2至200nm。 再者，第1介電體膜21至第4介電體膜33亦可爲1 層之介電體膜所構成的單層構造，亦可爲由2層以上之介 電體膜所構成的積層構造。第1介電體膜21至第4介電 體膜33的材料並無特別限制，然而以使用Si02、Si304、 AI2O3、AIN、Tao、ZnS、Ce〇2 等、Si、A1、Ta、Zn 的氧 化物、氮化物、硫化物、碳化物或這些的混合物爲宜。 反射膜3 4具有反射從光入射面1 3 a入射雷射光束， 再將雷射光束從光入射面1 3 a射出的功用，其厚度宜設定 爲2 0至2 0 0 nm。反射膜34的材料並無特別限制，然而以 使用主成分爲Ag或A1的合金爲宜，亦可使用Au或Pt 等。又，爲了防止反射膜34的腐蝕，亦可在反射膜34與 基體1 1之間設置防濕膜。該防濕膜可使用與第1介電體 膜21至第4介電體膜33相同的材料。此外，L0層20雖 不具有反射膜’然而亦可將3至15nm左右之薄反射膜設 置於L0反射層20。在此情況下，該反射膜的材料可使用 與反射膜3 4相同的材料。 將記錄於具有此種構造之光記錄媒體1 〇的資料再生 時’從光入射面1 3a照射具有200至45 Onm波長的雷射 光束’以檢測其反射光量。如上所述，L〇記錄膜22及 L1記錄膜32皆由相變化材料所構成者，由於其在結晶狀 態時之光反射率與非結晶狀態時之光反射率不同，故從光 -14- 1273579 (10) 入射面1 3 a照射雷射光束，使其聚焦於L 0記錄膜2 2和 L 1 S己錄膜3 2其中之一，而藉由檢測其反射光量，便可判 別雷射光束所照射的部分之L 0記錄膜2 2及L 1記錄膜3 2 是結晶狀態或非結晶狀態。 對光記錄媒體1 〇進行資料的記錄時，亦從光入射 面1 3a照射具有約45 Onm波長的雷射光束，使其聚焦於 L〇記錄膜22或L1記錄膜32，根據記錄的資料，將L0 記錄膜22及L 1記錄膜3 2的預定部分加熱至大於結晶化 溫度後’若加以快速冷卻，則該部分會形成非結晶狀態； 而將L0記錄膜22及L1記錄膜32的預定部分加熱至大 於結晶化溫度後，若加以緩緩冷卻，則該部分會形成結晶 狀態。非結晶狀態的部分稱爲「記錄標記（m a r k )」，記 錄資料形成由記錄標記之起點至終點的長度，和由終點至 下一個記錄標記之起點的長度。雖然各個記錄標記之長度 和記錄標記間之長度（邊緣（edge )間），並無特別的限 制，然而在採用（1，7 ) RLL之調變方式時，則設定爲與 2 T至8 T ( T是時脈週期）對應之長度的任一長度。 對L 1層3 0進行資料的記錄/再生時，雷射光束是經 由L0層20而照射在L1層32。因此L0層20必須具有充 分的光透過性，而如上所述，與L 1記錄膜3 2的模厚相比 較，L0記錄膜22的膜厚係以充分薄於L1記錄膜3 2的 膜厚之方式設計。 繼之，說明本實施方式之光記錄媒體1 〇的製造方法 -15- 1273579 (11) 第2圖至第5圖是顯示光記錄媒體10之製造方法的 步驟圖。 首先，如第2圖所示，使用印模（stamper ) 40，射 出成形具有訊號紋道1 1 a和紋間面1 1 b之基體1 1。其次 ，如第3圖所示，在形成有訊號紋道1 1 a和紋間面1 1 b之 基體11的大致整面，利用濺鍍法，依序形成反射膜34、 第4介電體膜33、L1記錄膜32和第3介電體膜31。藉 此方式，完成L1層3 0。並且，施行濺鍍後之L1記錄膜 32的狀態通常爲非結晶狀態。 接著，如第4圖所示，在L1層30上旋轉塗敷（spin co at )紫外線硬化性樹脂，並在其表面被覆印模4 1之狀 態下，透過印模4 1來照射紫外線，藉此方式，形成具有 訊號紋道1 2a和紋間面1 2b之中間層12。然後，如第5 圖所示，在形成有訊號紋道12a和紋間面1 2b之中間層 12的大致整面，利用濺鍍法，依序形成第2介電體膜23 、L0記錄膜22和第1介電體膜21。藉此方式，完成L0 層2 0。並且，施行濺鍍後之L0記錄膜22的狀態通常爲 非結晶狀態。 如第1圖所示，藉由在L0層20上旋轉塗敷（spin coat )紫外線硬化性樹脂，並照射紫外線，以形成光透過 層1 3。藉此方式，完成全部的成膜步驟。本說明書中， 將完成成膜步驟狀態下之光記錄媒體稱爲「光記錄媒體前 驅體」。 繼之，將光記錄媒體前驅體載置於雷射照射裝置的旋 -16- 1273579 (12) 轉台（未圖示）上，並使該旋轉台旋轉，同時，連續照射 沿著軌道方向之長度較短且垂直於軌道方向之長度較長的 矩形雷射光束，而每當光記錄媒體前驅體旋轉1圈時，便 會在垂直於軌道的方向挪移照射位置，藉此方式，可將矩 形的雷射光束照射於L0記錄膜22和L1記錄膜32的大 致整面。因此，因爲將構成L0記錄膜22及L1記錄膜32 的相變化材料加熱至大於結晶化溫度的溫度後，再加以緩 緩冷卻，故L0記錄膜22和L1記錄膜3 2實質上會整面 形成結晶狀態，也就是未記錄狀態。此步驟一般稱爲「初 期化步驟」。 完成該初期化步驟完成即完成了光記錄媒體1 〇。 對如此製造之光記錄媒體1 〇而言，如上所述，藉由 將雷射光束聚焦於L0記錄膜22和L1記錄膜32的其中 之一者，以形成記錄標記，即可記錄所期望的數位資料。 又，將資料記錄於光記錄媒體1 〇的L0記錄膜22和L1 記錄膜3 2後，如上所述，藉由將雷射光束聚焦於L0記錄 膜22和L1記錄膜3 2的其中之一者，以檢測反射光量， 俾得以再生所記錄的數位資料。 用以指定將記錄於L0記錄膜22和L1記錄膜3 2的 數位資料再生時之各種條件的資訊即爲「再生條件設定資 訊」，且該「再生條件設定資訊」以預先保存於該光記錄 媒體1 〇內爲宜。若預先將此種再生條件設定資訊保存在 光記錄媒體1 〇內，使用者實際上在進行資料的再生時， 可藉由利用資訊再生裝置來讀取該再生條件設定資訊，以 -17- 1273579 (13) 決定雷射光束的再生功率（p r )等再生條件。 就再生條件設定資訊來說’爲了決定對L0層20進行 資料再生時的再生功率（P r 0 )，和對L 1層3 1進行資料 再生時的再生功率（P r 1 )，至少必須包含所需的資料， 除此之外，對光記錄媒體1 〇進行資料再生時，爲了指定 所需的各種條件（再生線速度等），最好亦包含所需的資 訊。再生條件設定資訊可記錄爲顫線（Wobble)或訊洞， 亦可於L0記錄膜22及/和L1記錄膜32上記錄爲資料 。此外，不僅直接表示資料再生所需的各種條件，亦可藉 由指定預先儲存於資訊再生裝置內的各種條件的任一條件 ，間接地指定再生條件。 第6圖是顯示對光記錄媒體1 0進行資料記錄之再生 裝置50的主要部分槪略圖。 如第6圖所示，資訊再生裝置5 0具有用以令光記錄 媒體10旋轉的主軸馬達（spindle motor) 52;將波長λ 爲2 00至40 0左右的雷射光束照射在光記錄媒體10，同 時，亦接收反射光的光學讀寫頭53 ;控制主軸馬達52和 控制光學讀寫頭5 3之動作的控制器5 4 ;供給雷射驅動信 號至光學讀寫頭5 3的雷射驅動電路5 5 ;和供給透鏡（ lens )驅動信號至光學讀寫頭53的透鏡驅動電路56。光 學讀寫頭5 3上具有用以將雷射光束聚集於L0記錄膜22 和L1記錄膜3 2的接物鏡（未圖示），而其開口數（NA )以大於〇 · 7爲宜，最好是〇 . 8 5左右。 再者，如第6圖所示，控制器5 4包括聚焦伺服隨動 •18- 1273579 (14) 電路5 7、循軌伺服隨動電路5 8、和雷射控制電路5 9。當 聚焦伺服隨動電路5 7活性化時，旋轉中之光記錄媒體1 〇 的記錄面會成聚焦狀態，而當循軌伺服隨動電路5 8活性 化時，對於光記錄媒體1 〇的偏心信號軌道，雷射光束的 光點會成自動隨動狀態。 聚焦伺服隨動電路5 7和循軌伺服隨動電路5 8，分別 具有用以自動調整聚焦增益之自動增益控制功能及用以自 動調整循軌增益之自動增益控制功能.。又，雷射控制電路 5 9是形成雷射驅動電路5 5所供給的雷射驅動信號之電路 ’並根據記錄於光記錄媒體1 〇的再生條件設定資訊，形 成適當的雷射驅動信號。 並且，這些聚焦伺服隨動電路5 7、循軌伺服隨動電 路5 8和雷射控制電路5 9不須是組裝於控制器5 4內的電 路，亦可以是控制器54以外的個別零件。再者，這些構 造不須爲物理性電路，亦可爲在控制器54內執行的軟體 〇 使用由此種構造構成的資訊再生裝置5 0，對本實施 方式的光記錄媒體1 〇，進行資料的記錄時，如上所述’ 讀取記錄於光記錄媒體1 〇的再生條件設定資訊，並依此 來決定再生條件。因此，資訊再生裝置50對L0層20進 行資料的再生時，是依據所讀取的再生條件設定資訊，將 雷射光束再生功率設定爲Pr〇 ;而對L1層30進行資料的 再生時，是依據所讀取的再生條件設定資訊，將雷射光束 再生功率設定爲Prl。 -19- 1273579 (15) 本實施方式中，對L0層20進行資料再生時之再生功 率（PrO )，和對L1層30進行資料再生時之再生功率（ Prl )的關係是依據再生條件設定資訊，而設定爲pr〇 < Prl，較理想是設定爲Pr0/Prl<0.9。具體而言，PrO宜 設定爲〇·4至0.5mW，Prl宜設定爲〇·6至〇.7mW，又， Pr〇設定約〇.5mW且Prl設定爲〇.7mW左右更爲理想。 並且，再生功率（PrO、Prl )的値是照射雷射光束時盤面 的値。本實施方式中，將對L0層20進行資料再生時的再 生功率（PrO)設定較低的原因是僅爲了抑制L0層20之 再生劣化現象而已。 習知的技術爲，對具有複數個資訊記錄層的光記錄媒 體進行資料再生時，將離光入射面較遠處之資訊記錄層的 再生功率設定爲高於離光入射面較近處之資訊記錄層的再 生功率，藉此方式，提昇離光入射面較遠處之資訊記錄層 的再生感度（參考日本特開2000— 36130號公報）。然而 ，作爲本發明對象之新世代型的光記錄媒體，是使用波長 λ爲20 0至400左右的雷射光束，同時，用以聚集雷射光 束之接物鏡的開口數（ΝΑ )以設爲0.7以上爲宜，比較 理想的是〇 · 8 5左右，所以聚集之雷射光束單位面積的功 率非常高，而容易發生再生劣化現象。尤其是L0層20的 散熱性較低，故再生劣化現象會更顯著。因此可以說像以 往那樣依據再生感度來設定再生功率之方式實際上是不可 能的。 由此觀點可知，本實施方式中，對於L0層20之再生 -20- 1273579 (16) 功率（Ρι·0 )及L1層30之再生功率（Prl )是以可防止再 生劣化現象發生之位階（level )來制定，而且使用開口數 (NA)爲0.7以上，比較理想的爲0.85左右的接物鏡， 來聚集波長λ爲200至400左右的雷射光束進行再生時， 則以設定爲PrO < Prl爲宜，比較理想的是設定爲PrO/ Prl < 0.9 。 藉此方式，不僅可抑制易發生再生劣化現象之L0層 20發生再生劣化現象，亦可抑制L1層30之再生劣化現 象的發生。 如以上之說明，根據本發明對具有複數個資訊記錄層 的光記錄媒體進行資料再生時，可抑制再生劣化現象。 而且，所使用之雷射光束的波長越短越容易發生再生 劣化現象，同時，聚集雷射光束之接物鏡的開口數（NA )越大也越容易發生。因此，本發明使用之雷射光束的波 長（λ )和用以聚集雷射光束之接物鏡的開口數（NA ) 的比値（λ / ΝΑ )爲700nm以下時，例如：ΝΑ爲0.7以 上（尤其是0.85左右），雷射光束的波長Λ爲200至 4 5 0 n m時效果最好。 〔實施例〕 以下，具體說明本發明的實施例。 光記錄媒體1 〇的製造 首先，使用第2圖所示之印模4 0來進行聚碳酸酯的 射出成形’藉以製成訊號紋道1 1 a的深度和間距分別爲 -21 - 1273579 (17) 34nm和〇.32//m且厚度爲1.1mm的基體11。 繼之，將基體11搬入濺鍍裝置（未圖示）內，藉由 在基體1 1中形成訊號紋道1 1 a和紋間面1 1 b的大致整面 ，依序濺鍍Ag合金、ZnS和Si02的混合物（莫耳比=80 :20) 、AgSbTeGe和ZnS與Si〇2的混合物（莫耳比=80 :20)，以成膜厚度分別爲100nm、15nm、12nm和80nm 的反射膜34、第4介電體膜33、L1記錄膜32和第3介 電體膜31(L1層30)。 接著，將形成有L 1層3 0的基體1 1從濺鍍裝置搬出 ，然後，在第3介電體膜31上，旋轉塗敷（spin coat) 紫外線硬化性丙烯基樹脂。在旋轉塗敷有紫外線硬化性丙 嫌基樹脂的表面，如第4圖所示那樣於被覆印模4 1的狀 態下，透過印模4 1照射紫外線。藉以形成訊號紋道！ 2a 的深度和間距分別爲3 4nm及0.3 2 // m且厚度爲2 0 // m的 中間層1 2。 將形成有L 1層3 0及中間層1 2的基體1 1搬入濺鍍裝 置內’在形成有訊號紋道12a和紋間面12b之中間層12 的大致整面，依序濺鍍A12 〇 3、S b T e、和Z n S與S i Ο 2的 混合物（莫耳比=8 0 : 20 )，以成膜厚度分別爲7〇nm、 8nm、60nm的第2介電體膜23、l〇記錄膜22和第1介 電體膜21(L0層20)。 將形成有L1層30、中間層12和L0層20的基體1 1 從濺鍍裝置（未圖示）搬出，然後，藉由在第1介電體膜 21上’旋轉塗敷（spin coat )紫外線硬化性丙烯基樹脂並 -22- 1273579 (18) 照射紫外線，以形成厚度爲1 〇〇 // m的光透過層1 3。藉此 方式’完成光記錄媒體前軀體。 將該光記錄媒體前驅體載置於雷射照射裝置的旋轉台 (未圖示）上，使其旋轉，同時，連續照射沿著軌道方向 之長度較短且垂直於軌道方向之長度較長的矩形雷射光束 ’而每當光記錄媒體前驅體旋轉1圏時，便會在垂直於軌 道的方向挪移照射位置，因此，L0記錄膜22及L1記錄 膜3 2的整面會實質地初期化成結晶狀態。藉此方式，完 成本實施例使用的光記錄媒體1 〇。 資料的記錄 對於如此製造之光記錄媒體1 〇的L0記錄層20，將 記錄功率（Pw )、刪除功率（Pe )和基底功率（Pb )分 別設定爲6.0 m W、1 . 5 m W及〇 · 1 m W，以進行資料的記錄 ，繼之，對於L1記錄層3 0，將記錄功率（P w )、刪除功 率（Pe)和基底功率（Pb)分別設定爲l〇mW、3.8mW和 〇 · 1 m W，以進行資料的記錄。並且，記錄功率（P w )、刪 除功率（P e )和基底功率（P b )的値即爲照射雷射光束時 盤面的値。記錄時，將時脈頻率設定爲6 5.7 Μ H z ( T = 15.2ns ec )，記錄線速度設定爲5.7m / sec，並利用（1，7 )RLL的調變方式來形成混合信號。各記錄標記（2T至 8 τ )的形成所使用之雷射光束的脈衝數（雷射光束的功率 提昇至記錄功率（P w )的次數）是η 一1次（η是Τ的倍 數（2至8 ))。又，使用於記錄之雷射光束的波長是 -23- 1273579 (19) 4〇5nm，用以聚集雷射光束之接物鏡的開口數是〇.85。 資料的再生 然後，將再生功率（Pr〇、Prl )設爲各種位階（level )，並對記錄有資料之預定的相同軌道，進行1 00萬次的 資料再生，以測試其顫動（jitter )。顫動是利用時脈間 距分析器（T i m e I n t e r v a 1 A n a 1 y z e r，TIA )來測試時脈顫 動’以求得該再生信號的「顫動（σ )」，設限幅寬度爲 Tw，藉由cr / Tw ( % )算出。首先，將L0層20的測試 結果顯不在表1。 表1 再生次數 再生功^ 客（PrO) 〇.3mW 0.4mW 0.5mW 0.6mW 0.7mW 10次 無法測試 11.1% 10.8% 10.8% 10.9% 1000000 次 無法測試 11.1% 10.8% 12.3% 14.7% 由表1可知，對L0層20進行資料再生時，當再生次 數爲1 〇次時即使改變再生功率（P r 〇 )顫動幾乎不會改變 (約爲1 1 % );然而當再生功率（PrO )爲〇.6mW以上時 ，進行1 〇〇萬次的再生會使顫動大幅惡化。可認爲是對 L0層20進行資料再生時，若再生功率（Pr〇 )設爲 0.6mW以上時，會發生再生劣化之故。 另一方面’當再生功率（Pr〇)爲〇.4mW至0.5mW的 -24- 1273579 (20) 情況下，再生次數爲100萬次時的顫動與再生次數爲ίο 次時的顫動是一樣的’沒有發生再生劣化現象。此外，若 比較再生功率（p r 〇 )爲〇 . 4 m W時與0 · 5 m W時兩者的情況 ，可知再生功率爲〇.5mW時會獲致較良好的顫動。可認 爲是再生功率（PrO)越高，再生感度越高之故。 並且，將再生功率（PrO)設定爲〇.3mW時，則無法 利用感度不足來測試顫動。 由以上可知，對L0層20進行資料再生時，以將再生 功率（PrO )設爲0.4mW至0.5mW爲宜，比較理想的是設 爲約0.5mW。 繼而，將L 1層3 0的測試結果顯示在表2。 表2 再生次數 再生功率（Pr 1 ) 0.5mW 0.6mW 0.7mW 0.8 m W 10次 1 2.7 % 9.6 % 9.3 % 9.5 % 1 0 0 0 0 0 0 次 12.6% 9.6 % 9.3 % 1 2.9 %1273579 (1) Field of the Invention The present invention relates to a method for reproducing information from an optical recording medium, and more particularly to information reproduction by a rewritable optical recording medium having a plurality of information recording layers. The method. Further, the present invention relates to an information reproducing apparatus for reproducing information recorded on an optical recording medium, and more particularly to an information reproducing apparatus for reproducing information recorded on a rewritable optical recording medium having a plurality of information recording layers. Furthermore, the present invention relates to an optical recording medium, and more particularly to a rewritable optical recording medium having a plurality of information recording layers. [Prior Art] For a recording medium for recording digital data, a conventional CD or DVD representative Sexual optical recording media is widely used by consumers. In recent years, the demand for the expansion of the recording capacity of such optical recording media has gradually increased, and various proposals have been made for this purpose. As an example of the proposal, there is a proposal for forming a two-layer structure of an information recording layer included in an optical recording medium, and it is currently being applied to a DVD-Video or DVD-ROM for reproducing a dedicated optical recording medium. In such an optical recording medium for reproduction, the hole formed on the surface of the substrate is an information recording layer, and such a substrate has a structure in which an intermediate layer is laminated. In addition, in recent years, an optical recording medium (rewritable optical recording medium) in which a user can perform data overwriting has been proposed as an optical recording medium having a two-layer structure of an information recording layer (refer to JP-A-200 1 -2). (6) In the rewritable optical recording medium having a two-layer structure, the recording film and the dielectric film (protective film) formed by sandwiching the recording film are It is an information recording layer' and the information recording layer has a structure in which an intermediate layer is laminated. In the case of a recording film of a writable optical recording medium, a phase change material can be generally used, and data can be recorded by using a difference in reflectance between a crystalline state and an amorphous state. That is, in the unrecorded state, the recording film substantially forms a crystal state on the entire surface, and in a state where the material is recorded, a predetermined portion of the recording film is formed into an amorphous state, and a mark (mark) is formed. In order to change the phase change material in the crystalline state to an amorphous state, it can be rapidly cooled after heating to a temperature equal to or higher than the melting point. On the other hand, in order to change the amorphous phase change material into a crystalline state, it can be gradually cooled after heating to a temperature equal to or higher than the melting point. This heating and cooling can be performed by adjusting the power (output) of the laser beam. That is, by modulating the intensity of the laser beam. Not only can the data be recorded in the unrecorded state of the recording film, but different materials can be directly overwritten in the portion where the data has been recorded. In general, in order to heat the recording film to a temperature higher than the melting point, the power of the laser beam is a power set with a pulse waveform having an amplitude from the recording power (Pw) to the substrate power (Pb), for rapid cooling recording. Membrane, the power of the laser beam is set to the substrate power (Pb). Further, in order to heat the recording film to a temperature higher than the crystallization temperature, it is gradually cooled, and the power of the laser beam is set to the erasing power (Pe). At this time, the erasing power (pe) is a level set to a temperature at which the temperature of the recording film is larger than the temperature of crystallization but not reaching the melting point, whereby so-called solid phase deletion is performed. 1273579 (3) Here, in the rewritable optical recording medium having the two-layer structure of the information recording layer, 'the recording/reproduction of the data is performed by focusing the laser beam on any of the information recording layers, so When the light is incident on the information recording layer on the far side (hereinafter referred to as "L1 layer"), when the data is recorded/reproduced, the information recording layer is closer to the light incident surface (hereinafter referred to as "L 〇". Layer") to illuminate the laser beam. Therefore, the L 0 layer must have sufficient light transmittance. Therefore, no matter whether or not a reflective film is provided on the L 0 layer, the film thickness is generally required to be thin. However, according to the inventors of the present invention, in the rewritable optical recording medium having the two-layer structure of the information recording layer, it is easy to occur in the L0 layer, and the recording state of the recorded film deteriorates with the reproduction of the data. The so-called "regeneration deterioration phenomenon". It is considered that regardless of whether or not the L Q layer is provided with a reflection film, the film thickness of the L0 layer should be made thin, so that the heat dissipation property is lower than that of the reflection film L1 layer having a sufficient film thickness. That is to say, metal is generally used as the material of the reflective film, so the heat generated by the irradiation of the laser beam in the L1 layer is rapidly dissipated through the highly thermally reflective film, and on the other hand, it is considered to be due to L. The 0 layer does not have such a layer having high thermal conductivity, so the heat generated by the irradiation of the laser beam cannot be quickly dissipated, which causes regeneration deterioration. On the other hand, in recent years, the ratio (λ / NA ) of the wavelength (λ ) of the laser beam used for recording/reproduction and the number of apertures (n A ) of the objective lens for collecting the laser beam is set to 7 0 0 . Below nm, for example, by increasing the NA to 0.7 or more, especially to about 〇85, and simultaneously shortening the wavelength λ of the laser beam to about 200 to 450 nm to reduce the laser beam of the poly-8 - 1273579 (4 ) The focal spot diameter is used to attempt to record large-capacity digital data. Thus, in a system for recording/reproducing data by using a high-NA objective lens to collect a short-wavelength laser beam, since the energy of the laser beam per unit area is very high, the degradation of the L0 layer is deteriorated. Very significant. SUMMARY OF THE INVENTION An object of the present invention is to provide an information reproducing method for an information reproducing method of a rewritable optical recording medium having a plurality of information recording layers, and suppressing the phenomenon of reproduction degradation. Further, another object of the present invention is to provide an information reproducing apparatus for recording information on a rewritable optical recording medium having a plurality of information recording layers, and which is capable of suppressing reproduction degradation. Further, another object of the present invention is to provide an optical recording medium which has a plurality of information recording layers and which can suppress reproduction deterioration. An object of the present invention is to achieve an information reproducing method for reproducing information by irradiating a laser beam from a light incident surface to an optical recording medium having at least a first and a second information recording layer, and is characterized in that: The wavelength of the above-mentioned laser beam is set to λ, and when the number of openings of the objective lens for collecting the above-mentioned laser beam is set to ΝΑ, it is set to be 1/NA'700 nm, and is recorded on the first information recording layer. When the information is reproduced, the laser beam is set to the first power; and when the information recorded on the second information recording layer is reproduced, the laser beam is set to a second power different from the first power. In a preferred embodiment of the present invention, the first information recording layer is located closer to the light incident surface side than the second information recording layer, and the first power is smaller than the second power. . In a more preferred embodiment of the present invention, when the first power is set to Pr〇' and the second power is set to Prl, Pr0/Prl < 0.9 is set to perform information reproduction. In a more preferred embodiment of the invention, the laser beam has a wavelength λ of 200 to 450 nm. The above object of the present invention is achieved by an information reproducing apparatus that reproduces information by irradiating a laser beam from a light incident surface to an optical recording medium having at least a first and a second information recording layer laminated thereon, and is characterized in that: When the wavelength of the above-mentioned laser beam is set to λ, and the number of apertures of the objective lens for collecting the above-mentioned laser beam is set to ΝΑ, it is set to /NAS 700 nm, and information recorded on the first information recording layer is set. When the reproduction is performed, the laser beam is set to the first power, and when the information recorded on the second information recording layer is reproduced, the laser beam is set to a second power different from the first power. The above object of the present invention is achieved by an optical recording medium having at least a first and a second information recording layer laminated thereon and capable of reproducing information by irradiating a laser beam from a light incident surface, characterized in that: The wavelength of the beam is set to λ, and when the number of apertures of the objective lens for collecting the laser beam is set to ΝΑ, it is set to; I / NAS 700 nm, and has the required setting information, and the pair is recorded in the above first When the information of the information recording layer is reproduced, the laser beam is set to the first power; and when the information recorded on the second element-10-1273579 (6) recording layer is reproduced, the laser beam is set. It is a second power different from the first power described above. According to a preferred embodiment of the present invention, there is provided a light transmitting layer which is an optical path of the laser beam, and the light transmitting layer has a thickness of 30 to 200 / /m. According to the present invention, for a light having a plurality of information recording layers When the recording medium performs information reproduction, it is possible to suppress the deterioration of reproduction. [Embodiment] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a cross-sectional view showing the structure of an optical recording medium 1 according to a preferred embodiment of the present invention. As shown in FIG. 1, an optical recording medium 10 according to an embodiment of the present invention has a substrate 11, an intermediate layer 12, a light transmitting layer 13, an L0 layer 20 provided between the intermediate layer 12 and the light transmitting layer 13, and is provided on the substrate 1. The L1 layer 30 between 1 and the intermediate layer 12. The L0 layer 20 constitutes an information recording layer located on the near side of the light incident surface 13a, and is composed of the first dielectric film 2 1 , the L0 recording film 22 and the second dielectric film 23 . Further, the L 1 layer 30 constitutes an information recording layer located on the far side of the light incident surface 13 3 , which is composed of the third dielectric film 3 1 , L 1 recording film 3 2 , the fourth dielectric film 3 3 and The reflective film 34 is composed of. Therefore, the optical recording medium 1 of the present embodiment has two layers of information recording layers (L0 layer 2 0 and L 1 layer 30). The substrate 11 is a disk-shaped substrate having a thickness of about 1 · 1 mm, and has a function of ensuring the mechanical strength of the light 11 - 1273579 (7) recording medium 10, and has a signal groove 1 la on the surface thereof. And land 1 lb. When recording/reproducing data on the L1 layer 30, these signal tracks 11a and/or land 11b have the function of a guide track as a laser beam. Although the depth of the signal track 1 la is not particularly limited, it should be set to 10 to 40 nm, and the pitch of the signal track 1 la should be set to 0.2 to 0.4 // m. The material of the substrate 11 can be made of various materials such as glass, ceramic or resin. Among these, it is preferable to use a resin in view of ease of formation. Such a resin has, for example, a polycarbonate resin, an olefin resin, a propylene-based resin, an epoxy resin, a polystyrene resin, a polyethylene resin, a polypropylene resin, an anthracene resin, a fluorine-based resin, ABS resin, urethane resin, and the like. Among them, polycarbonate resin or olefin resin is most suitable in terms of processability. However, since the base 11 is not the optical path of the laser beam, it is not necessary to have high light transmittance. The intermediate layer 12 has a function of keeping the L0 layer 20 and the L1 layer 30 at a sufficient distance, and is provided with a signal groove 12a and a land 12b on the surface thereof. When recording/reproducing data on the L0 layer 20, these signal tracks 12a and/or land 12b have the function of a guide track as a laser beam. The depth and pitch of the signal track 12a should be set to be the same as the depth and pitch of the signal track 1 1 a provided on the substrate 11. Further, the material of the intermediate layer 12 is not particularly limited, but an ultraviolet curable acryl-based resin is preferably used. When recording/reproducing data on the L 1 layer 30, the intermediate layer 12 will be the optical path of the laser beam, so it is necessary to have a sufficiently high light transmittance of -12-1273579 (8). The light transmission layer 13 is an optical path of the laser beam, and also constitutes the light incident surface 13a, and its thickness is preferably set to about 3 〇 to 2 〇〇 / / ηη. The material of the light-transmitting layer 13 is not particularly limited, but as with the intermediate layer 12, it is preferred to use an ultraviolet curable acryl-based resin. As described above, since the light transmitting layer 13 is an optical path of the laser beam, it is necessary to have sufficiently high light transmittance. L 0 recording film 2 2 and L 1 g have been recorded | Wu 3 2 is a material composed of a phase change material 'using a characteristic in which the reflectance in the crystalline state is different from the reflectance in the amorphous state' recording. The specific material of the L 0 recording film 2 2 and the L1 recording film 32 is not particularly limited, but an SbTe-based material is preferably used. The SbTe-based material may be only SbTe, and as the additive, InSbTeGe, AglnSbTe, AgSbTeGe, AglnSbTeGe or the like to which In, Te, Ge, Ag, or the like is added may be used. Here, when data is recorded/reproduced in the L 1 layer 30, the L0 recording film 22 is an optical path of the laser beam, and therefore it is necessary to have sufficient light transmittance, so the film thickness of the L 0 recording film 2 2 is It is designed in such a manner that it is sufficiently thinner than the film thickness of the recording film 3 2 of l 1 . Specifically, the film thickness of the L1 recording film 32 is preferably set to be about 3 to 20 nm, and the film thickness of the L 0 recording film 22 is preferably set to be 0.3 to 0.8 times the film thickness of the L 1 recording film 32. The first dielectric film 21 and the second dielectric film 23 which are provided by sandwiching the L0 recording film 22 have a function as a protective film for the L0 recording film 22, and are provided by sandwiching the L1 recording film 32. The third dielectric film 3 1 and the fourth dielectric film 3 3 have a function as a protective film for the L 1 recording film 32. The thickness of the first dielectric film 21 is preferably set to 2 to 200 nm, and the thickness of the second dielectric body 1273579 (9) is preferably set to 2 to 200 nm, and the thickness of the third dielectric film 31 is preferably set to be The thickness of 2 to 200 nm 'and the fourth dielectric film 33 is preferably set to 2 to 200 nm. Further, the first dielectric film 21 to the fourth dielectric film 33 may be a single layer structure composed of a dielectric film of one layer, or may be composed of a dielectric film of two or more layers. Laminated structure. The materials of the first dielectric film 21 to the fourth dielectric film 33 are not particularly limited, but SiO 2 , Si 304 , AI 2 O 3 , AIN, Tao, ZnS, Ce 〇 2 , etc., Si, A1, Ta, Zn are used. Oxides, nitrides, sulfides, carbides or mixtures of these are preferred. The reflection film 34 has a function of reflecting a laser beam incident from the light incident surface 13 a and then emitting the laser beam from the light incident surface 13 3 a, and the thickness thereof is preferably set to 20 to 200 nm. The material of the reflective film 34 is not particularly limited. However, it is preferred to use an alloy having a main component of Ag or Al, and Au or Pt may be used. Further, in order to prevent corrosion of the reflective film 34, a moisture-proof film may be provided between the reflective film 34 and the substrate 11. The moisture-proof film can be made of the same material as the first dielectric film 21 to the fourth dielectric film 33. Further, although the L0 layer 20 does not have a reflective film', a thin reflective film of about 3 to 15 nm may be provided in the L0 reflective layer 20. In this case, the material of the reflective film may be the same material as that of the reflective film 34. When reproducing the material recorded on the optical recording medium 1 此种 having such a configuration, a laser beam having a wavelength of 200 to 45 Onm is irradiated from the light incident surface 13a to detect the amount of reflected light. As described above, the L〇 recording film 22 and the L1 recording film 32 are both composed of a phase change material, and since the light reflectance in the crystalline state is different from the light reflectance in the amorphous state, the light-14- 1273579 (10) The incident surface 13 3 a illuminates the laser beam to focus on one of the L 0 recording film 2 2 and the L 1 S recording film 3 2 , and by detecting the amount of reflected light, the laser can be discriminated The L 0 recording film 2 2 and the L 1 recording film 3 2 of the portion irradiated by the light beam are in a crystalline state or an amorphous state. When data is recorded on the optical recording medium 1 ,, a laser beam having a wavelength of about 45 Onm is also irradiated from the light incident surface 13a to be focused on the L〇 recording film 22 or the L1 recording film 32, based on the recorded data. After the predetermined portion of the L0 recording film 22 and the L1 recording film 32 is heated to be larger than the crystallization temperature, 'if it is rapidly cooled, the portion is formed into an amorphous state; and the recording of the L0 recording film 22 and the L1 recording film 32 is made. After partial heating to a temperature greater than the crystallization temperature, if it is slowly cooled, the portion will form a crystalline state. The portion of the amorphous state is referred to as "recording mark (m a r k )", and the recorded data forms the length from the start point to the end point of the record mark, and the length from the end point to the start point of the next record mark. Although there is no particular limitation on the length of each recording mark and the length between the recording marks (between edges), when using the (1,7) RLL modulation method, it is set to 2 T to 8 T. (T is the clock cycle) any length corresponding to the length. When data is recorded/reproduced on the L 1 layer 30, the laser beam is irradiated onto the L1 layer 32 via the L0 layer 20. Therefore, the L0 layer 20 must have sufficient light transmittance, and as described above, the film thickness of the L0 recording film 22 is sufficiently thinner than the film thickness of the L1 recording film 32 as compared with the mold thickness of the L1 recording film 32. Way design. Next, a method of manufacturing the optical recording medium 1 of the present embodiment will be described. -15- 1273579 (11) FIGS. 2 to 5 are step diagrams showing a method of manufacturing the optical recording medium 10. First, as shown in Fig. 2, a substrate 11 having a signal track 11a and a land 11b is injection-molded using a stamper 40. Next, as shown in FIG. 3, the reflective film 34 and the fourth dielectric body are sequentially formed by sputtering on the substantially entire surface of the substrate 11 on which the signal track 11a and the land 11b are formed. The film 33, the L1 recording film 32, and the third dielectric film 31 are provided. In this way, the L1 layer 30 is completed. Further, the state of the L1 recording film 32 after the sputtering is usually in an amorphous state. Next, as shown in Fig. 4, the ultraviolet curable resin is spin-coated on the L1 layer 30, and the surface of the stamp 41 is applied to the surface of the L1 layer 30, and the ultraviolet rays are irradiated through the stamp 41. In this manner, the intermediate layer 12 having the signal track 12a and the land 12b is formed. Then, as shown in Fig. 5, on the substantially entire surface of the intermediate layer 12 on which the signal track 12a and the land 12b are formed, the second dielectric film 23 and the L0 recording film are sequentially formed by sputtering. 22 and the first dielectric film 21. In this way, the L0 layer 20 is completed. Further, the state of the L0 recording film 22 after the sputtering is usually in an amorphous state. As shown in Fig. 1, the light-transmitting layer 13 is formed by spin-coating the ultraviolet curable resin on the L0 layer 20 and irradiating the ultraviolet rays. In this way, all film forming steps are completed. In the present specification, the optical recording medium in the state in which the film formation step is completed is referred to as "optical recording medium precursor". Then, the optical recording medium precursor is placed on the rotary-16-1273579 (12) turntable (not shown) of the laser irradiation device, and the rotary table is rotated while continuously irradiating the length along the track direction. a rectangular laser beam having a shorter length and perpendicular to the length of the track, and each time the precursor of the optical recording medium is rotated one turn, the irradiation position is moved in a direction perpendicular to the track, whereby the rectangular shape can be The laser beam is irradiated onto substantially the entire surface of the L0 recording film 22 and the L1 recording film 32. Therefore, since the phase change material constituting the L0 recording film 22 and the L1 recording film 32 is heated to a temperature higher than the crystallization temperature and then gradually cooled, the L0 recording film 22 and the L1 recording film 32 are substantially entirely flat. A crystalline state, that is, an unrecorded state, is formed. This step is generally referred to as the "initialization step." Upon completion of the initialization step, the optical recording medium 1 is completed. With the optical recording medium 1 thus manufactured, as described above, by focusing the laser beam on one of the L0 recording film 22 and the L1 recording film 32 to form a recording mark, the desired recording can be recorded. Digital data. Further, after the data is recorded on the L0 recording film 22 and the L1 recording film 32 of the optical recording medium 1 as described above, the laser beam is focused on one of the L0 recording film 22 and the L1 recording film 32 as described above. In order to detect the amount of reflected light, 俾 can reproduce the recorded digital data. The information for specifying various conditions for reproducing the digital data recorded on the L0 recording film 22 and the L1 recording film 32 is "reproduction condition setting information", and the "reproduction condition setting information" is stored in advance in the optical recording. Media 1 is appropriate. If such reproduction condition setting information is stored in the optical recording medium 1 in advance, the user can actually read the reproduction condition setting information by using the information reproduction device when the data is reproduced, -17- 1273579 (13) Determine the regeneration conditions such as the reproducing power (pr ) of the laser beam. In the reproduction condition setting information, at least the reproduction power (P r 0 ) at the time of data reproduction for the L0 layer 20 and the reproduction power (P r 1 ) when data reproduction is performed on the L 1 layer 3 1 must include at least In addition to the required data, in order to reproduce the data on the optical recording medium 1 最好, it is preferable to include the required information in order to specify various conditions (reproducing line speed, etc.). The reproduction condition setting information can be recorded as a wobble or a hole, and can also be recorded as data on the L0 recording film 22 and/or the L1 recording film 32. Further, not only the various conditions required for data reproduction but also any conditions of various conditions previously stored in the information reproducing apparatus can be specified, and the reproduction conditions can be indirectly specified. Fig. 6 is a schematic diagram showing the main part of the reproducing apparatus 50 for recording data on the optical recording medium 10; As shown in Fig. 6, the information reproducing apparatus 50 has a spindle motor 52 for rotating the optical recording medium 10; and a laser beam having a wavelength λ of about 200 to 40 is irradiated onto the optical recording medium 10 At the same time, an optical pickup 53 that also receives reflected light; a controller 5 that controls the spindle motor 52 and controls the operation of the optical pickup 5; and a laser drive that supplies the laser drive signal to the optical pickup 53 The circuit 5 5; and a supply lens (lens) drive signal to the lens drive circuit 56 of the optical pickup 53. The optical pickup head 53 has an objective lens (not shown) for collecting the laser beam on the L0 recording film 22 and the L1 recording film 32, and the number of openings (NA) is preferably greater than 〇·7. It is best to 〇. 8 5 or so. Furthermore, as shown in Fig. 6, the controller 54 includes a focus servo follower 18-18273579 (14) circuit 57, a tracking servo follower circuit 58, and a laser control circuit 59. When the focus servo follower circuit 57 is activated, the recording surface of the optical recording medium 1 in rotation is in a focused state, and when the tracking servo follower circuit 58 is activated, the eccentricity of the optical recording medium 1 is eccentric. The signal track, the spot of the laser beam will automatically follow the state. The focus servo follower circuit 57 and the tracking servo follower circuit 5 8 respectively have an automatic gain control function for automatically adjusting the focus gain and an automatic gain control function for automatically adjusting the tracking gain. Further, the laser control circuit 5.9 is a circuit </ RTI> which forms a laser driving signal supplied from the laser driving circuit 55, and forms an appropriate laser driving signal based on the reproduction condition setting information recorded on the optical recording medium 1 。. Further, the focus servo follower circuit 57, the tracking servo follower circuit 58 and the laser control circuit 59 need not be circuits incorporated in the controller 504, but may be individual components other than the controller 54. Further, these structures do not need to be physical circuits, and the information reproducing device 50 having such a configuration may be used for the software 执行 executed in the controller 54, and the optical recording medium 1 of the present embodiment is subjected to data. At the time of recording, the reproduction condition setting information recorded on the optical recording medium 1 is read as described above, and the reproduction condition is determined accordingly. Therefore, when the information reproduction device 50 reproduces the data on the L0 layer 20, the information is set based on the read reproduction condition, and the laser beam reproduction power is set to Pr 〇; and when the data is reproduced on the L1 layer 30, The laser beam reproducing power is set to Prl according to the read regeneration condition setting information. -19- 1273579 (15) In the present embodiment, the relationship between the reproducing power (PrO) at the time of data reproduction in the L0 layer 20 and the reproducing power (Prl) when data is reproduced in the L1 layer 30 is based on the reproduction condition setting information. It is set to pr 〇 < Prl, and is preferably set to Pr0/Prl < 0.9. Specifically, PrO should be set to 〇·4 to 0.5 mW, Prl should be set to 〇·6 to 7.7 mW, and Pr 〇 is set to about 55 mW and Prl is set to about 7.7 mW. Further, the 再生 of the reproducing power (PrO, Prl) is the 盘 of the disk surface when the laser beam is irradiated. In the present embodiment, the reason why the reproduction power (PrO) at the time of data reproduction in the L0 layer 20 is set low is to suppress the deterioration of the L0 layer 20 only. The conventional technique is to set the regenerative power of the information recording layer farther from the light incident surface to be higher than the information from the light incident surface when data reproduction is performed on the optical recording medium having a plurality of information recording layers. The reproducing power of the recording layer, in this way, enhances the regenerative sensitivity of the information recording layer farther from the light incident surface (refer to Japanese Laid-Open Patent Publication No. 2000-36130). However, as a new generation optical recording medium to which the present invention is applied, a laser beam having a wavelength λ of about 20 to 400 is used, and at the same time, the number of apertures (ΝΑ) of the objective lens for collecting the laser beam is set to 0.7 or more is preferable, and it is preferable that it is about 8·8 5 or so, so the power per unit area of the collected laser beam is very high, and regenerative deterioration is likely to occur. In particular, the heat dissipation of the L0 layer 20 is low, so that the phenomenon of regeneration deterioration is more remarkable. Therefore, it can be said that the method of setting the regenerative power according to the regenerative sensitivity as in the past is practically impossible. From this point of view, in the present embodiment, the regeneration of the L0 layer 20, -20-1273579 (16) power (Ρι·0), and the regenerative power (Prl) of the L1 layer 30 are steps that prevent regenerative degradation from occurring ( Level ) is set, and the number of openings (NA) is 0.7 or more, preferably about 0.85, to collect a laser beam having a wavelength λ of about 200 to 400 for regeneration, and then set to PrO < Prl is preferred, and it is desirable to set it to PrO/Prl < 0.9. By this means, it is possible to suppress not only the occurrence of regenerative deterioration of the L0 layer 20 which is prone to occurrence of regenerative deterioration but also the occurrence of regenerative deterioration of the L1 layer 30. As described above, according to the present invention, when data is reproduced on an optical recording medium having a plurality of information recording layers, the phenomenon of reproduction deterioration can be suppressed. Further, the shorter the wavelength of the laser beam used, the more likely the regenerative deterioration phenomenon occurs, and the larger the number of apertures (NA) of the objective lens for collecting the laser beam, the more likely it is to occur. Therefore, when the ratio (λ / ΝΑ ) of the wavelength (λ ) of the laser beam used in the present invention and the number of apertures (NA ) of the objective lens for collecting the laser beam is 700 nm or less, for example, ΝΑ is 0.7 or more ( Especially around 0.85), the best effect is obtained when the wavelength of the laser beam is 至200 to 450 nm. [Examples] Hereinafter, examples of the invention will be specifically described. Production of Optical Recording Media 1 首先 First, the injection molding of polycarbonate is performed using the stamp 40 shown in Fig. 2, whereby the depth and pitch of the signal track 1 1 a are made to be -21273579 (17 A substrate 11 having a thickness of 34 nm and 〇.32//m and a thickness of 1.1 mm. Then, the substrate 11 is carried into a sputtering apparatus (not shown), and an Ag alloy is sequentially sputtered by forming a substantially entire surface of the signal track 11 a and the land 1 1 b in the substrate 1 1 . a mixture of ZnS and SiO 2 (mol ratio = 80:20), AgSbTeGe and a mixture of ZnS and Si〇2 (mol ratio = 80:20), with a film thickness of 100 nm, 15 nm, 12 nm and 80 nm, respectively. 34. The fourth dielectric film 33, the L1 recording film 32, and the third dielectric film 31 (L1 layer 30). Next, the substrate 1 1 on which the L 1 layer 30 is formed is carried out from the sputtering apparatus, and then the ultraviolet curable acryl-based resin is spin-coated on the third dielectric film 31. The surface on which the ultraviolet curable acrylic resin was spin-coated was irradiated with ultraviolet rays through the stamp 41 in a state where the stamp 41 was coated as shown in Fig. 4 . In order to form a signal pattern! The intermediate layer 12 of 2a has a depth and a pitch of 34 nm and 0.32 // m and a thickness of 2 0 // m, respectively. The substrate 1 1 in which the L 1 layer 30 and the intermediate layer 12 are formed is carried into the sputtering apparatus. In the substantially entire surface of the intermediate layer 12 on which the signal track 12a and the land 12b are formed, A12 is sequentially sputtered. 3. S b T e, and a mixture of Z n S and S i Ο 2 (mol ratio = 80: 20), and a second dielectric film 23 having a film thickness of 7 〇 nm, 8 nm, and 60 nm, respectively. The recording film 22 and the first dielectric film 21 (L0 layer 20). The substrate 1 1 on which the L1 layer 30, the intermediate layer 12, and the L0 layer 20 are formed is carried out from a sputtering apparatus (not shown), and then 'spin coat' is formed on the first dielectric film 21. The ultraviolet curable acryl-based resin and -22- 1273579 (18) were irradiated with ultraviolet rays to form a light-transmitting layer 13 having a thickness of 1 〇〇//m. In this way, the optical recording medium precursor is completed. The optical recording medium precursor is placed on a rotating table (not shown) of the laser irradiation device to be rotated, and the length of the continuous irradiation along the track direction is short and the length perpendicular to the track direction is long. The rectangular laser beam 'when the optical recording medium precursor is rotated by 1 turn, the irradiation position is shifted in the direction perpendicular to the track. Therefore, the entire surface of the L0 recording film 22 and the L1 recording film 32 is substantially initialized. Crystallized state. In this way, the optical recording medium 1 used in the embodiment is completed. Recording of data For the L0 recording layer 20 of the optical recording medium 1 thus manufactured, recording power (Pw), erasing power (Pe), and base power (Pb) were set to 6.0 mW, 1.5 m W, and 〇, respectively. · 1 m W for data recording, and then, for the L1 recording layer 30, the recording power (P w ), the erasing power (Pe), and the base power (Pb) are set to l〇mW, 3.8 mW, and 〇· 1 m W for recording of data. Also, the 记录 of the recording power (P w ), the deleted power (P e ), and the base power (P b ) is the 盘 of the disk surface when the laser beam is irradiated. When recording, the clock frequency is set to 6 5.7 Μ H z ( T = 15.2 ns ec ), the recording linear velocity is set to 5.7 m / sec, and the mixed signal is formed by the modulation method of (1, 7 ) RLL. The number of pulses of the laser beam (the number of times the power of the laser beam is increased to the recording power (P w )) used for the formation of each recording mark (2T to 8 τ ) is η - 1 (η is a multiple of Τ (2 To 8)). Further, the wavelength of the laser beam used for recording is -23 - 1273579 (19) 4 〇 5 nm, and the number of apertures of the objective lens for collecting the laser beam is 〇.85. Data reproduction Then, the reproduction power (Pr〇, Prl) is set to various levels, and 100,000 times of data reproduction is performed on the same orbit in which the data is recorded, to test the jitter. The tremor is to test the clock pulsation by using a clock interval analyzer (TIA I nterva 1 A na yzer, TIA) to obtain the "vibration (σ)" of the reproduced signal, and the limiting width is Tw. Cr / Tw ( % ) is calculated. First, the test results of the L0 layer 20 are not shown in Table 1. Table 1 Regeneration number of regeneration power (PrO) 〇.3mW 0.4mW 0.5mW 0.6mW 0.7mW 10 times can not be tested 11.1% 10.8% 10.8% 10.9% 1000000 times can not test 11.1% 10.8% 12.3% 14.7% As shown in Table 1 When data is reproduced on the L0 layer 20, even if the number of reproductions is 1 〇, even if the regenerative power (P r 〇) is changed, the chattering hardly changes (about 1 1 %); however, when the regenerative power (PrO) is 〇. When it is 6mW or more, the regeneration of 1 million times will greatly deteriorate the chattering. When data reproduction is performed on the L0 layer 20, it is considered that when the regenerative power (Pr 〇 ) is 0.6 mW or more, regeneration deterioration occurs. On the other hand, when the regenerative power (Pr〇) is -24 to 1273579 (20) of 〇.4mW to 0.5mW, the vibration at the time of the reproduction of 1 million times is the same as the vibration at the time of the number of reproductions of ίο times. 'No regeneration deterioration occurred. In addition, if the comparison of the regenerative power (p r 〇 ) is 〇 . 4 m W and 0 · 5 m W , it can be seen that the regenerative power is 〇.5 mW, which results in better chattering. It can be considered that the higher the regenerative power (PrO), the higher the regenerative sensitivity. Also, when the regenerative power (PrO) is set to 〇3mW, the jitter cannot be tested with insufficient sensitivity. As described above, when data reproduction is performed on the L0 layer 20, it is preferable to set the regenerative power (PrO) to 0.4 mW to 0.5 mW, and it is preferable to set it to about 0.5 mW. Then, the test results of the L 1 layer 30 are shown in Table 2. Table 2 Number of regenerations Regeneration power (Pr 1 ) 0.5mW 0.6mW 0.7mW 0.8 m W 10 times 1 2.7 % 9.6 % 9.3 % 9.5 % 1 0 0 0 0 0 0 times 12.6% 9.6 % 9.3 % 1 2.9 %
由表2可知，對L 1層3 0進行資料再生時，將再生功 率（Prl )設定爲0.8mW以上時，會發生再生劣化現象。 發生再生劣化的再生功率（Prl=0.8mW)高於L0層20中 發生再生劣化的功率（Pr0 = 0.6mW)是因爲L0層20和 L 1層3 0具有散熱性的差所導致。 此外，在0.7mW以下的區域再生功率（Pri)越高可 -25- 1273579 (21) 獲致越良好的顫動。可認爲是由於再生功率（Pr 1 )越高 再生感度會越增加之故。 由以上可知，對L 1層3 0進行資料再生時，以將再生 功率（Pr〇 )設爲〇.6mW至〇.7mW爲宜，比較理想的是設 爲約0.7mW。 【圖式簡單說明】 第1圖是槪略地顯示本發明較佳實施方式之光記錄媒 體1 〇的構造剖視圖。 第2圖是顯示光記錄媒體1〇之一部分（基體11的形 成）的製造步驟圖。 第3圖是顯示光記錄媒體1〇之一部分（L1層30的 形成）的製造步驟圖。 第4圖是顯示光記錄媒體1 〇之一部份（透明中間層 1 2的形成）的製造步驟圖。 第5圖是顯不光記錄媒體1〇之一部份（l〇層20的 形成）的製造步驟圖。 第6圖是槪略地顯示用以對光記錄媒體1 〇進行資料 的再生之資訊再生裝置50的主要部分圖。 〔圖號說明〕 1 〇 :光記錄媒體 1 1 :基體 1 la、12a :訊號紋道 - 26- 1273579 (22) 1 1 b、1 2 b :紋間面 1 2 :中間層 1 3 :光透過層 1 3 a :光入射面 20 ： L0 層 2 1 :第1介電體膜 2 2 : L 0記錄膜 23 :第2介電體膜 3 0 ·· L1 層 3 1 :第3介電體膜 3 2 : L 1記錄膜 3 3 :第4介電體膜 34 :反射膜 4 0、4 1 :印模 5 0 :資訊再生裝置 5 2 :主軸馬達 5 3 :光學讀寫頭 5 4 :控制器 5 5 :雷射驅動電路 5 6 :透鏡驅動電路 5 7 :聚焦伺服隨動電路 5 8 :循軌伺服隨動電路 5 9 :雷射控制電路 -27-As is clear from Table 2, when data reproduction is performed on the L 1 layer 30, when the regenerative power (Prl) is set to 0.8 mW or more, regenerative deterioration occurs. The regenerative power at which regenerative degradation occurs (Prl = 0.8 mW) is higher than the power at which regenerative degradation occurs in the L0 layer 20 (Pr0 = 0.6 mW) because the L0 layer 20 and the L 1 layer 30 have a difference in heat dissipation. In addition, the higher the regenerative power (Pri) in the region below 0.7 mW, the better the jitter can be obtained from -25 to 1273579 (21). It can be considered that the higher the regenerative power (Pr 1 ), the more the regenerative sensitivity increases. As described above, when data is reproduced in the L 1 layer 30, it is preferable to set the regenerative power (Pr 〇 ) to 〇.6 mW to 〇.7 mW, and it is preferable to set it to about 0.7 mW. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the structure of an optical recording medium 1 较佳 according to a preferred embodiment of the present invention. Fig. 2 is a view showing a manufacturing step of displaying one portion of the optical recording medium 1 (formation of the substrate 11). Fig. 3 is a view showing a manufacturing step of displaying one portion of the optical recording medium 1 (formation of the L1 layer 30). Fig. 4 is a view showing the manufacturing steps of a part of the optical recording medium 1 (formation of the transparent intermediate layer 12). Fig. 5 is a view showing the manufacturing steps of a part of the recording medium 1 (the formation of the layer 10). Fig. 6 is a view schematically showing the main part of the information reproducing apparatus 50 for reproducing the data on the optical recording medium 1A. [Description of the figure] 1 〇: Optical recording medium 1 1 : Substrate 1 la, 12a: Signal track - 26 - 1273579 (22) 1 1 b, 1 2 b : Interlaced surface 1 2 : Intermediate layer 1 3 : Light Transmission layer 13 3 a : light incident surface 20 : L0 layer 2 1 : first dielectric film 2 2 : L 0 recording film 23 : second dielectric film 3 0 ·· L1 layer 3 1 : third dielectric Body film 3 2 : L 1 recording film 3 3 : 4th dielectric film 34 : Reflecting film 4 0, 4 1 : Stamp 5 0 : Information reproducing device 5 2 : Spindle motor 5 3 : Optical head 5 4 : Controller 5 5 : Laser drive circuit 5 6 : Lens drive circuit 5 7 : Focus servo follower circuit 5 8 : Track servo follower circuit 5 9 : Laser control circuit -27-